The invention relates to a drain module or feedthrough module especially adapted for convenient incorporation into retaining walls constructed of interlocking retaining blocks.
Various manufacturers, including Keystone Retaining Wall Systems, Inc., of Minneapolis, Minn., Amastone Retaining Walls of Littleton, Colo., and Diamond Wall Block Systems Inc., of Brooklyn Park, Minn. manufacture and market specialized interlocking retaining blocks for construction of retaining walls which may be utilized to retain earthen terraces and the like. Frequently it is desirable that such retaining walls have one or more drains or feedthroughs.
Until now, the only known way of providing drains or feedthroughs in such retaining walls has been to "leave out" a few retaining blocks where the drain or feedthrough is needed and place a short section of ordinary pipe in the gap left by the omitted blocks and then fill the gaps between the section of pipe and the surrounding retaining blocks to provide a seal. This technique leaves much to be desired because (1) the prior technique does not conform to the interlocking scheme of the wall and leaves a potential weakness in the system, (2) the gaps filled with cement, grout, or other filler material do not match the face contour of the retaining blocks of which the retaining wall is constructed, (3) because of vibration, thermal cycling, etc. "slivers" of cement or filler usually break away, leaving unsightly gaps that require frequent repair, and (4) the prior technique is unsatisfactory from the viewpoint of construction cost, because considerably more labor is required to seal the feedthrough pipe section with the cement, grout, etc. than is required to lay an ordinary interlocking retaining block.